The MP who passed a dossier of paedophile allegations to the Home Office in the 1980s told his family the details were "explosive".
Geoffrey Dickens, who died in 1995, said it would "blow the lid off" the lives of powerful and famous child abusers, his son has told the BBC.
Barry Dickens said he would have been "hugely angered" that the allegations had not been properly investigated.
Labour is demanding a fresh inquiry into the missing dossier.
It comes after one of the party's MPs called for the then Home Secretary Leon Brittan to make public what he knew about paedophiles operating "in and around" Westminster in the 1980s.
'Disappointed and frustrated'
Geoffrey Dickens, a long-standing campaigner against child abuse, passed the dossier of allegations to Lord Brittan, who has said he passed it on to his officials and raised concerns about some of the allegations with the director of public prosecutions.
His son Barry Dickens told the BBC's Matt Prodger: "I would like Lord Brittan to name the very next person he handed it on to.
"And where did it end up? There must have been a person who was the last to handle it.
"My father thought that the dossier at the time was the most powerful thing that had ever been produced, with the names that were involved and the power that they had."
He said the MP would have would have been "hugely angered, disappointed and frustrated" that the allegations had not been properly investigated.
The Home Office said that a search for the dossier in 2013 had found a letter from Lord Brittan to Geoffrey Dickens which said that the allegations had been acted on.
The review concluded that the "credible" elements of the dossier which had "realistic potential" for further investigation were passed to prosecutors and the police while other elements were either "not retained or destroyed".
"It just seems so suspicious that something so important could just go missing," Barry Dickens said.
Mr Dickens said he did not know the details of what was in the dossier but "it was talked about in the family, discussions now and then, sort of 'Wait and see what happens - this is going to blow everything apart. These people won't know what hit them'."
Around the time that the dossier was handed in, Mr Dickens said the MP's London flat and his constituency home were both broken into and ransacked within the same week, but that "nothing was taken".
"They weren't burglaries," he added. "They were break-ins for a reason. We can only presume they were after something that dad had that they wanted."
Labour has demanded a "proper investigation" into the way the Home Office handled the evidence contained in Mr Dickens' dossier, dubbing the Home Office review "lamentable".
The opposition said the work was carried out by just two officials and took just four weeks.
"This is not good enough," said shadow home secretary Yvette Cooper.
"The lack of proper answers from the Home Office are just increasing the confusion and concern rather than getting to the bottom of this."
The Labour chairman of the Home Affairs Select Committee, Keith Vaz, has written to the most senior civil servant in the Home Office asking questions about its review.
And separately, Labour has repeated its long-standing demand for a review into the findings of existing abuse inquiries to make sure child protection is adequate in future.
A Downing Street spokesman earlier rejected calls to publish in full the 2013 review of paperwork, saying: "My understanding is that the executive summary reflects very fully the report."
He added: "If there are allegations, evidence of wrongdoing that people have they should bring that to the attention of the relevant authorities including the police."
Deputy Prime Minister Nick Clegg, who worked for Lord Brittan in Brussels in the 1990s, also said the police were in the "best position" to investigate the allegations and he did not want anything - such as a public inquiry - to "cut across that or disrupt that".
Labour MP Mr Danczuk, who has been pressing Lord Brittan to reveal what he knew about the dossier's contents, is calling for a "Hillsborough-style" inquiry to prevent allegations involving politicians being "swept under the carpet".
Mr Danczuk, who has investigated claims of abuse by ex-MP Sir Cyril Smith, insisted there was "no reason" why the dossiers, which he said could include evidence indentifying child sex abusers, should have been destroyed by the Home Office.
The Metropolitan Police's Operation Fernbridge is investigating allegations of child sexual abuse in the late 1970s and 1980s at the former Elm Guest House in Barnes, the scene of alleged parties involving MPs and other members of the establishment.
Greater Manchester Police are investigating allegations of abuse by Sir Cyril Smith at Knowl View, a Rochdale children's home which closed in 1994. Officers are also looking at claims the authorities covered it up.
But calls are growing for an over-arching national inquiry, with hearings held in public, to get to the truth of what happened and deliver justice to the alleged victims. More than 120 MPs have signed a letter to the home secretary calling for an inquiry.